Estudo do papel da ecto-5'-nucleotidase no contexto da inflamação avaliando parâmetros citológicos, bioquímicos, moleculares e imagens de μPET/CT em Zebrafish

• Ano de defesa: 2016
• Autor(a) principal: Nazario, Luiza Reali
• Orientador(a): Silva, Rosane Souza da
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Pontifícia Universidade Católica do Rio Grande do Sul
• Programa de Pós-Graduação: Programa de Pós-Graduação em Biologia Celular e Molecular
• Departamento: Faculdade de Biociências
• País: Brasil
• Palavras-chave em Português: ADENOSINA; INFLAMAÇÃO; BIOFARMACÊUTICA; BIOLOGIA CELULAR
• Área do conhecimento CNPq: CIENCIAS BIOLOGICAS::BIOLOGIA GERAL
• Link de acesso: http://tede2.pucrs.br/tede2/handle/tede/6927

The LPS mechanism of action is still not completely elucidated on vertebrates like fish, and indeed differs from higher vertebrates. In zebrafish, LPS is capable of increasing the recruitment of immune cells and the expression of genes related to the immune response. The purinergic system has a great relation to the regulation of the immune system and inflammatory responses. The nucleotide ATP is able to induce cytokine secretion, recruitment and differentiation of immune cells. ATP can be dephosphorylated sequentially generating adenosine. In the context of inflammation adenosine serves as an innate immunomodulatory molecule. The control of adenosine extracellular levels is performed by nucleoside transporters and ecto-5'-nucleotidase. The ecto-5'-nucelotidase is an ectonucleotidase with pacemaker role in the production of adenosine and is one of the focuses of this study. Considering the analysis of the input images approach to the study of inflammation context, it is known that in rodents the uptake of 18F-FDG, an analogue of glucose, is increased under inflammation, which generates a differential image. The micro Positron Emission Tomography/ Computed Tomography (μPET /CT) is used for research in small animals and take images using a radiopharmaceutical. The use of μPET/CT contributes with information at the molecular, structural and functional level and allows too monitor the effect of drugs in physiological / pathological situations in the range of a small animal as the zebrafish. The technology μPET/CT is relatively new and so far there are no published scientific studies applying radiopharmaceuticals in zebrafish. In this context, the aim of the project was to study the involvement of the enzyme ecto-5'-nucleotidase in the development of inflammation induced by LPS using the cytological, biochemical, molecular and image (μPET) in different tissues of adult zebrafish (Danio rerio). To induce inflammation in zebrafish, the animals were injected with a solution of LPS (10 ug/g body weight, i.p) after being subjected to anesthesia (tricaine 0.1 g/L). The animals were kept for 2 hours or 24 hours in this treatment. For confirmation of inflammation were analyzed the gene expression of specific markers (tnf-α and cox-2) in encephalon, heart, kidney and intestine and differential counts of cells of the immune system. The activity and expression of ecto-5'-nucleotidase enzyme was analyzed in the encephalon, heart, kidney and intestine of control and treated animals. To keep the animals in μPET/CT was performed anesthetic concentration curve (tricaine - 0.1, 0.12, 0.15 g/L) and standardized an apparatus to keep the fish in the presence of water, but yet still. A curve of time after injection of 18F-FDG was performed to obtain images in μPET/CT (0, 10, 20 and 30 min) for standardizing the radiation quantitation in a gamma counter (15, 30, 60 90 and 120 min). Exposure to the LPS was able to increase the tnf-α expression in nearly all tissues studied (heart, kidney and intestine) and cox-2 in the kidney. The number of active peripheral blood white cells was also increased, confirming the induction of the inflammatory response. Hydrolysis of AMP in animals injected with LPS was increased in the heart in 24 hpi [72% compared to control] with no change in gene expression of ecto-5'-nucleotidase. The gene expression of ecto-5'-nucleotidase was adjusted temporarily in the kidney and intestine without altering the enzyme activity. After patterning images with μPET/ CT and quantitation radiation by gamma counter for each organ examined, 30 minutes was defined as the best time for the biodistribution of 18F-FDG. After acquiring inflamed animal μPET images it was not identified changes in the uptake of 18F-FDG compared to the control. Tissue quantification radiation registered a decrease in bone samples in animals treated with LPS, while other tissues have not changed. These data indicate that zebrafish responds to LPS by altering gene expression of specific markers, especially in kidney, and activation of white blood cells. The inflammation appears to be accompanied by a fine adjustment tissue-specific expression and activity of ecto-5'-nucleotidase in response to the inflammatory process. Although inflammation has been confirmed, the registration images by μPET and radiation determination in different tissues have not been able to register differences in metabolic activity in animals treated with LPS. However, standardization of these techniques provides an advance in the use of radiopharmaceuticals in small animals, such as zebrafish.